Prosthetic valves may be used to treat cardiac valvular disorders. Native heart valves, such as aortic, pulmonary, tricuspid, and mitral valves, serve critical functions in assuring a forward flow of an adequate supply of blood through the cardiovascular system. Heart valves can be rendered less effective by congenital malformations, inflammatory processes, infectious conditions, or diseases. Damage to the valves typically results in serious cardiovascular compromise or death. For many years the definitive treatment for heart valve disorders has been surgical repair or replacement of valves by way of open heart surgery. Such surgeries, however, are highly invasive and prone to many complications. As such, elderly and frail patients with defective heart valves often go untreated.
Transvascular techniques have been developed for introducing and implanting a prosthetic heart valve using a flexible catheter in a manner that is much less invasive than open heart surgery. For example, a prosthetic valve may be mounted in a crimped state on an end portion of a flexible catheter and advanced through a blood vessel of a patient until the valve reaches an implantation site of a defective native valve. The prosthetic valve may then be expanded to a functional size at the implantation site such as by inflating a balloon on which the valve is mounted.
Another technique for implanting a prosthetic aortic valve is a transapical approach where a small incision is made in the chest wall of the patient and the catheter is advanced through the apex (i.e., bottom tip) of the heart. Transapical techniques are disclosed in U.S. Patent Application Publication No. 2007/0112422, which is hereby incorporated by reference. As with the transvascular approach, the transapical approach may include a balloon catheter having a steering mechanism for delivering a balloon-expandable prosthetic heart valve through an introducer to a defective native valve. The balloon catheter may include a deflecting segment just proximal to the distal balloon to facilitate positioning of the prosthetic heart valve in a proper orientation within an aortic annulus.
The above techniques and others provide numerous options for high operative risk patients with aortic valve disease to avoid the consequences of open heart surgery and cardiopulmonary bypass. While devices and procedures for aortic valves exist, such catheter-based procedures are not necessarily applicable to the mitral valve due to distinct differences between aortic and mitral valves. For example, the mitral valve has a complex subvalvular apparatus, known as chordae tendineae, which are not present in the aortic valve and can complicate valve delivery and placement.
When the native mitral valve fails to function properly, a prosthetic valve replacement may help restore proper functionality. Compared to the aortic valve, however, which has a relatively round and firm annulus, the mitral valve annulus can be relatively less firm and more unstable. Consequently, it may not be possible to secure a prosthetic valve that is designed for the aortic valve within the native mitral valve annulus by relying solely on friction from the radial force of an outer surface of a prosthetic valve pressed against the native mitral annulus. Accordingly, it may be beneficial to add ventricular anchors to prosthetic mitral valves to help secure the prosthetic valve within the native mitral valve annulus.
However, the addition of ventricular anchors may result in a relatively large crimp profile, including as large as 40 F (i.e., French Gauge). Further, a connection area between the ventricular anchors and the prosthetic valve may experience a relatively high degree of strain during crimping which may give rise to damage to the prosthetic valve during delivery into a patient. A prosthetic mitral valve having ventricular anchors that do not result in an overly large crimp profile or do not increase the size of the crimp profile and comprising a connection area that is better suited to withstand stresses and strains during delivery into the patient.
While the present disclosure is subject to various modifications and alternative forms, specific embodiments thereof have been shown by way of example in the drawings and will herein be described in detail. The invention should be understood to not be limited to the particular forms disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the present disclosure.